The prevalence of resistant bacterial pathogens is rendering current antibiotics ineffective, and making it essential that new drugs be developed to fight infection. Defensins are antimicrobial peptides that protect man against bacterial and viral infections and have a wide range as potential anti-infective therapeutics. This proposal identifies Lipid II, an essential precursor in bacterial membrane biogenesis, as a potential target of defensin antibacterial activity for the first time. The overall objective of our study is to define functional and structural interactions between defensins and Lipid II. In the long term, we aim to apply the knowledge gained in our research towards the development of defensin-based antibiotic compounds targeting Lipid II to combat Gram-positive pathogenic infections. PUBLIC HEALTH RELEVANCE: The escalating frequency of antibiotic resistant infections combined underscores the critical need to develop novel antibiotics. This project describes for the first time the interaction between defensins, naturally occurring antimicrobial compounds in humans and Lipid II, essential in the formation of bacterial membranes. Our research sheds new light on how defensins kill bacteria and is an important first step towards the development of these natural peptides as novel, effective antibiotic agents to combat infections.